Medical instrument

ABSTRACT

A medical instrument includes a housing, a stylet having a portion in the housing, a cannula coaxially receiving the stylet and having a portion in the housing, and a member coupled to the housing. The stylet and the cannula are movable between an extended position and a retracted position. The member, e.g., a lever, is configured to move the stylet and the cannula from the extended position to the retracted position.

TECHNICAL FIELD

The invention relates to medical instruments.

BACKGROUND

A biopsy needle instrument can be used to obtain a tissue specimen formicroscopic examination, e.g., to determine malignancy, while preferablysubjecting the patient to the least trauma. In some embodiments, theinstrument has of a long, thin probe, called a stylet, within aclose-fitting hollow needle, called a cannula. The stylet has a notchinto which tissue can prolapse when the stylet enters the tissue.

During use, a firing device first projects the stylet into tissue,followed immediately by the cannula. As the cannula slides over thestylet, the cannula severs from the surrounding mass tissue that hasprolapsed into the notch of the stylet, and captures the prolapsedtissue as a specimen within the notch. The instrument can then bewithdrawn and the piece of tissue removed from the stylet.

SUMMARY

The invention relates to medical instruments.

In one aspect, the invention features a medical instrument including ahousing, a stylet, a cannula, and a lever. The stylet has a portion inthe housing and is movable between an extended position and a retractedposition. The cannula coaxially receives the stylet and has a portion inthe housing. The cannula is movable between an extended position and aretracted position. The lever is coupled, for example, pivotally, to thehousing. The lever is configured to move, for example, sequentially, thestylet from the extended position to the retracted position, and to movethe cannula from the extended position to the retracted position.

Embodiments may include one or more of the following features. Theengaging element engages with the housing when the cannula is in theretracted position. The instrument further includes a linkage attachedto the lever, the linkage being engageable with the cannula block tomove the cannula to the retracted position. The instrument furtherincludes a stylet block attached to a proximal end of the stylet, and alatch in the housing, the latch and the stylet block engaging when thestylet is in the retracted position. The instrument further includes alinkage attached to the lever, the linkage being engageable with thestylet block to move the stylet to the retracted position. Theinstrument further includes a first trigger engageable with the latch torelease the stylet from the retracted position. The first triggerpivotally moves the latch to disengage the latch from the stylet block.The instrument further includes a second trigger engageable with thelatch to release the stylet from the retracted position.

The instrument can further include a cannula block attached to aproximal end of the cannula, the cannula block having an engagingelement capable of releasably holding the cannula in the retractedposition.

The instrument can further include a stylet block attached to a proximalend of the stylet, a cannula block attached to a proximal end of thecannula, and a linkage attached to the lever, the linkage capable ofbeing in a first position in which the linkage is engageable with thecannula block to move the cannula to the retracted position withoutmoving the stylet block, and in a second position in which the linkageis engageable with the stylet block to move the stylet to the retractedposition.

Embodiments may include one or more of the following features. Theinstrument further includes a first trigger configured to release thestylet from the retracted position. The first trigger is located at aproximal end of the housing. The first trigger and the lever are locatedon opposing surfaces of the housing. The instrument further includes asecond trigger configured to release the stylet from the retractedposition. The instrument further includes a lock engageable with thelever when the stylet block is in the retracted position. The instrumentfurther includes an indicator capable of being in a conditionrepresentative of when the stylet is in the second retracted position.

The instrument can further include a first trigger configured to holdthe stylet in the retracted position, and a second trigger engageablewith the first trigger, wherein the first and second triggers areconfigured to release the stylet from the retracted position. The firsttrigger can be pivotally attached to the housing. In some embodiments,the first trigger has a proximal end, and the second trigger has adistal end configured to engage with the proximal end of the firsttrigger. The proximal and distal ends can be angled.

In another aspect, the invention features a medical instrument includinga housing, a stylet, a cannula, a lever, and a linkage. The a stylet hasa portion in the housing and is movable between an extended position anda retracted position. The cannula coaxially receives the stylet and hasa portion in the housing. The cannula is movable between an extendedposition and a retracted position. The lever is pivotally coupled to thehousing. The linkage is attached to the lever. The linkage is capable ofbeing in a first position in which the linkage is capable of moving thecannula to the retracted position without moving the stylet, and in asecond position in which the linkage is capable of moving the stylet tothe retracted position. The instrument can further include two triggersconfigured to release the stylet from the retracted position.

In another aspect, the invention features a medical instrument includinga housing, a stylet attached to the housing, the stylet being movablebetween an extended position and a retracted position, and an indicatorassociated with the housing, the indicator providing a visual indicationof the position the stylet by a change in color.

In another aspect, the invention features a medical instrument includinga housing, a stylet attached to the housing, the stylet being movablebetween an extended position and a retracted position, and an indicatorassociated with the housing, the indicator providing a visual indicationof the position the stylet by a change in symbol.

In another aspect, the invention features a method including actuating alever to move a stylet from a first extended position to a secondretracted position, and actuating the lever to move a cannula from athird extended position to a fourth retracted position.

Embodiments may include one or more of the following features. Themethod further includes releasing the lever after the stylet is moved tothe second retracted position. The method further includes locking thelever after the cannula is moved. The method further includes sliding atrigger to release the stylet from the second retracted position. Themethod further includes pushing a trigger to release the stylet from thesecond retracted position. The stylet is moved without moving thecannula. The method further includes pushing a first trigger or a secondtrigger to release the stylet from the retracted position. Pushing thesecond trigger can move the first trigger out of engagement with thestylet.

In another aspect, the invention features a method including pivotallyactuating a lever to move a stylet from an extended position to aretracted position.

In another aspect, the invention features a method including pivotallyactuating a lever to move a cannula from an extended position to aretracted position.

In another aspect, the invention features a medical instrument includinga housing, a stylet attached to the housing, the stylet being movablebetween an extended position and a retracted position, and two triggersassociated with the housing, wherein the triggers are capable ofreleasing the stylet from the retracted position.

One of the triggers can be at a proximal end of the housing. One of thetriggers can be slidably associated with the housing.

In another aspect, the invention features a medical instrument includinga housing, a stylet having a portion in the housing, the stylet beingmovable between an extended position and a retracted position, a cannulacoaxially receiving the stylet and having a portion in the housing, thecannula being movable between an extended position and a retractedposition, and a member coupled to the housing, the member being capableof moving the stylet from the extended position to the retractedposition, and when separately engaged, moving the cannula from theextended position to the retracted position. The member can include alever. The member can be engaged by a user's hand, e.g., palm and/orfingers. Embodiments of the aspect of the invention may include one ormore of the features described above and below, in any combination.

Embodiments may have one or more of the following advantages. Theinstrument can be relatively easy to load prior to firing theinstrument. The lever of the instrument provides good mechanicaladvantage and is used to load the stylet and the cannula with the samemotion. The instrument includes two trigger mechanisms, which enhancesthe versatility and convenience of the instrument. For example,depending on a target site and/or preference of a user, a radiologistcan prefer to use a side trigger, while a urologist can prefer the reartrigger.

Other aspects, features, and advantages of the invention will beapparent from the description of the preferred embodiments thereof andfrom the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an embodiment of a biopsy instrument.

FIGS. 2A and 2B are exploded, perspective views of the biopsy instrumentof FIG. 1, at different angles.

FIGS. 3A, 3B, 3C, 3D, and 3E illustrate the biopsy instrument of FIG. 1at various stages of operation.

FIG. 4A is a schematic diagram of an embodiment of a biopsy instrumentin a rest position; and FIG. 4B is a schematic diagram of the instrumentof FIG. 4A in a cocked position.

DETAILED DESCRIPTION

Referring to FIGS. 1, 2A, 2B, and 3A, a biopsy instrument 20 includes ahousing 22, a stylet 24, a cannula 26, a lever 28 pivotally attached tothe housing, a side trigger 36, and a rear trigger 38. Housing 22includes a left shell 30 and a right shell 32 (as shown in Figures) thatare bonded together. Stylet 24 and cannula 26 have portions locatedwithin housing 22 and are configured to be axially movable relatively toeach other, between retracted positions and extended positions. As shownin FIG. 3A, stylet 24 and cannula 26 are in their extended positions.During use, stylet 24 and cannula 26 are loaded or cocked to theirretracted positions, ready to be triggered. When stylet 24 and cannula26 are triggered, they rapidly move distally to their extendedpositions, e.g., to collect a tissue specimen that has prolapsed into anotch 40 of the stylet. Lever 28 is connected to a linkage 44 configuredto move stylet 24 and cannula 26 from their extended positions to theirretracted or loaded positions. In particular, lever 28 is part of amechanism that is used to load both stylet 24 and cannula 26 to theirretracted positions. After stylet 24 and cannula 26 are loaded, eitherside trigger 36 or rear trigger 38 can be used to release the stylet andthe cannula to their extended positions.

Referring to FIGS. 2A, 2B, and 3A, cannula 26 is generally a hollowsheath, e.g., made of stainless steel, that receives stylet 24. At itsdistal end 27, cannula 26 is configured to sever tissue that hasprolapsed into notch 40. From distal end 27, cannula 26 extends intohousing 22 where the cannula is attached to an axially movable (arrow A)cannula block 42. Cannula block 42 includes a raised portion 46 thatengages with linkage 44 during use (described below), and twodeflectable tabs 48 that can engage with notches or lips (not shown)integrally formed on housing 22 to hold cannula 26 and cannula block 42in their retracted positions. A compression spring 50 engages cannulablock 42 and biases the cannula block distally. Spring 50 can be, e.g.,a stainless steel spring having a spring rate of 9.77 lb/in.

Stylet 24 is slidably and coaxially located in cannula 26. Stylet 24 hasa distal end 34 configured to penetrate tissue and notch 40 forcollecting a tissue sample. Examples of suitable stylet 24 and cannula26 configurations are exemplified by the ASAP™ Automated Biopsy Systemhaving a Delta Cut® needle or a Channel Cut® needle (available fromBoston Scientific Corp., Natick, Mass.), and described in Chu, U.S. Pat.No. 5,989,196, hereby incorporated by reference. From distal end 34,stylet 24 extends into housing 22 where stylet is attached to an axiallymovable stylet block 52. At its distal portion, stylet block 52 includesa distal post 54 and a distal wall 56, both of which engage with linkage44 when stylet 24 is moved to its retracted position. At its proximalportion, stylet block 52 includes a proximal wall 58 that is used tohold stylet block 52 in its retracted position, and a proximal post 60.Proximal post 60 can engage with an axially movable lever lock 62, whichis used to lock lever 28 in a closed position before stylet 24 andcannula 26 are released to their extended positions. Stylet block 52further includes two deflectable tabs 64 configured to engage with tabs48 of cannula block 42 to disengage tabs 48 from housing 22. Acompression spring 65 engages stylet block 52 and biases the styletblock distally.

Lever 28 is configured to load cannula 26 and stylet 24 to theirretracted positions. Lever 28 is connected to housing 22 by a link 66having a pin 68, which serves as an axis about which the lever rotates(arrow B). In some embodiments, a torsion spring (not shown) is attachedto pin 68 to bias lever 28 toward an open position (FIG. 3A). Lever 28is connected to a linkage 44 via a pin 45, and a hook 70 (FIG. 2A). Atorsion spring (not shown) is attached to pin 45 to bias linkage 44toward stylet block 52. As described below, during use, linkage 44engages with cannula block 42 and stylet block 52. Linkage 44 furtherincludes a curved portion 72 that engages with distal post 54 of styletblock 52. Hook 70 engages with protrusions 74 of lever lock 62 to holdlever 28 in a closed position.

Instrument 20 further includes a mechanism 76 to hold stylet block 52and to release the stylet block from its retracted position. Mechanism76 includes a rear latch 78, side trigger 36, and rear trigger 38. Rearlatch 78 includes a pin 80 and is mounted in housing 22 such that therear latch can pivot about the length of the pin (arrow C). Rear latch78 further includes a hook portion 82, two side members 84 having curvedends 86, and a rear plate 87. Hook portion 82 is configured to engagewith, e.g., hook on to, proximal wall 58 of stylet block 52 to hold thestylet block in its retracted position.

Side trigger 36 and rear trigger 38 are configured to move rear latch 78such that hook portion 82 can disengage from proximal wall 58. Sidetrigger 36, which is axially slidable (arrow A), includes a side button85, an end member 88 having a ramped surface 90, and an elongate member92 connecting the side button and the end member. Ramped surface 90contacts and engages with curved ends 86 of side members 84. When sidebutton 85 is pulled proximally, end member 88 also moves proximally. Asa result, ramped surface 90 engages with curved ends 86 and pivots rearlatch 78 such that hook portion 82 can lift and disengage from proximalwall 58. Rear trigger 38 is movably mounted to housing 22 and isconfigured to engage with rear plate 87. In particular, when depressed,rear trigger 38 pushes against rear plate 87. As a result, rear latch 78pivots about pin 80, and hook portion 82 can disengage from proximalwall 58.

In some embodiments, instrument 20 also includes a visual indicator 92that shows when stylet 24 has been loaded to its retracted position.Indicator 92 includes one or more windows 94 formed in housing 22 thatallow a user to detect a change in the position of stylet block 52. Forexample, window(s) 94 can be formed on housing 22 such that tabs 64 ofstylet block 52 cover the window(s) when the stylet block is in itsextended position. When stylet block 52 is retracted, tabs 64 slide awayfrom window(s) 94 and uncover interior portions of instrument 20. Theinterior portions can be colored, e.g., red, for enhanced visibility. Inother embodiments, window(s) 94 can be aligned with the proximal portionof stylet block 52 having a first color, e.g., green, and the distalportion of the stylet block can have a second color, e.g., red. Whenstylet block 52 is moved from its extended position to its retractedposition, the color visible through window(s) changes from the firstcolor to the second color to indicate that instrument 20 is loaded.Alternatively or in addition, instrument 20 can include window(s)aligned with cannula block 42 to indicate the position of the cannulablock. For example, cannula block 42 can be formed with portions withdifferent colors as described above.

FIGS. 3A–3E illustrate a sequence of the operation of instrument 20.Referring to FIG. 3A, instrument 20 is in its rest position, e.g., astaken out of its packaging. Cannula block 42 and stylet block 52 are attheir most distal, extended positions. Lever 28 is in its open position,and linkage 44 is adjacent to raised portion 46 of cannula block 42.Lever lock 62 is shown in a distal position.

To load or move cannula block 42 and stylet block 52 to their retractedpositions, lever 28 is actuated, e.g., closed, two times. Referring toFIG. 3B, when lever 28 is actuated the first time, linkage 44 pivots andengages with raised portion 46 of cannula block 42. As a result, cannulablock 42 and cannula 26 are pushed proximally until tabs 48 engage withhousing 22, thereby holding the cannula block and the cannula in theirretracted positions (FIG. 3B). Cannula block 42 compresses againstspring 50. Lever 28 is then released to its open position, e.g., aidedby the torsional spring (not shown) attached to pin 68.

Referring to FIG. 3C, when lever 28 is returned to its open position,linkage 44 engages with distal wall 56 of stylet block 52. The torsionspring (not shown) attached to pin 45 of linkage 44 helps bias the tipof the linkage toward stylet block 52. Lever 28 is then actuated to loadstylet block 52 and stylet 24 to their loaded, retracted positions. Whenlever 28 is actuated, linkage 44 pushes against distal wall 56 and movesstylet block 52 and stylet 24 proximally. Referring to FIG. 3D, asstylet block 52 is pushed further proximally, distal post 54 engages,e.g., contacts, with curved portion 72 of linkage 44. As stylet block 52is pushed to its retracted position, distal post 54 pushes linkage 44out of engagement with distal wall 56 and stylet block 52. When styletblock 52 is at its retracted position, hook portion 82 of rear latch 78engages with proximal wall 58 of the stylet block and holds the styletblock in its retracted position. At the same time, when stylet block 52is in its retracted position, proximal post 60 pushes lever lock 62proximally (FIG. 3D). As a result, hook 70 of lever 28 can engage withprotrusions 74 of lever lock 62 to hold the lever in a closed position(FIG. 3E). Stylet block 52 compresses against spring 65. Instrument 20is ready to be triggered or fired.

To fire instrument 20, distal end 34 of stylet 24 is placed adjacent toa target area, and either side trigger 36 or rear trigger 38 can beactuated. To actuate side trigger 36, side button 85 is pulledproximally, e.g., using an index finger, which causes end member 88 tomove proximally. As a result, curved ends 86 of side members 84 areadvanced over ramped surface 90, which causes rear latch 78 to pivotabout pin 80, thereby lifting hook portion 82 out of engagement withproximal wall 58 of stylet block 52. Upon disengagement, stylet block 52and stylet 24 are propelled distally by the spring force of spring 65,which allows the stylet to penetrate the targeted area. Stylet block 52then strikes cannula block 42, which disengages tabs 48 of the cannulablock from housing 22. In particular, the ramped configuration of thetips of tabs 64 help to wedge tabs 64 between tabs 48 and housing 22 todisengage tabs 48 and cannula block 42 from the housing. Upondisengagement, cannula block 42 and cannula 26 are propelled distally bythe spring force of spring 50, which allows the cannula to slide overstylet 24 and to sever a specimen that has prolapsed into notch 40 ofthe stylet.

Instrument 20 can then be withdrawn. Lever 28 can be returned to itsopen position by slightly depressing the lever to allow lever lock 62 tomove (e.g., distally) and to disengage from hook 70, e.g., similar tothe operation of a lockable grip vise. The specimen can be removed fromnotch 40 by actuating lever 28 once to retract cannula 26. The specimencan be placed on a slide or in a preservative solution. If desired,lever 28 can be actuated to retract and load stylet 24 to collectanother specimen.

Rear trigger 38 is actuated by distally pushing the rear trigger, whichpushes against rear plate 87. As a result, rear latch 78 pivots aboutpin 80, and hook portion 82 is lifted out of engagement with proximalwall 58 of stylet block 52. Upon disengagement, stylet 24 and cannula 26are propelled distally as described above.

In other embodiments, mechanism 76 used to hold stylet block 52 and torelease the stylet block from its retracted position can be modified.Referring to FIGS. 4A and 4B, instrument 100 (generally the same asinstrument 20 except as described below) includes a mechanism 102 havinga side trigger 104 and a rear trigger 106. Side trigger 104 includes anelongated body 108 having a side button 110, a distal portion 112, and aproximal portion 114. Body 108 is pivotally attached to housing 22 atpivot 116. Distal portion 112 is a generally elongated, curved memberthat engages portions of housing 22 to bias side button 110 out of thehousing (or downward as shown in FIG. 4A). Distal portion 112 alsobiases proximal portion 114 upward (as shown in FIG. 4A) via pivot 116.Proximal portion 114 includes a projection 118 configured to engage withstylet block 52, specifically, a notch 120 defined by the stylet block.Proximal portion 114 terminates with an angled surface 122. Rear trigger106 includes a rear button 124 integrally form with a proximal portion126 that terminates with an angled surface 128. Angled surface 128contacts angled surface 122, but for clarity, the surfaces are shownspaced from each other.

Operation of instrument 100 is similar to operation of instrument 20.The user retracts cannula block 42 by actuating lever 28 once. When theuser actuates lever 28 again, stylet block 52 is moved proximally untilprojection 118 engages notch 120, thereby holding the stylet block inits retracted position (FIG. 4B). Projection 118 is biased upward (asshown in FIG. 4A) by distal portion 112 and pivot 116 to facilitateengagement with notch 120.

To fire instrument 100, either side trigger 104 or rear trigger 106 canbe actuated. To actuate side trigger 104, side button 108 is pushed intohousing 22, which overcomes biasing force of distal portion 112 andcauses projection 118 to move down (arrow X, as shown in FIG. 4B) viapivot 116. As a result, projection 118 disengages from notch 120, andstylet block 52 and cannula block 42 can be propelled distally asdescribed above.

Rear trigger 106 is actuated by pushing rear button 124 distally (arrowY). As a result, angled surface 128 contacts, e.g., slides over, angledsurface 122, thereby moving proximal portion 114 and projection 118downward (arrow X) and out of engagement with notch 120. Stylet block 52and cannula block 42 are propelled distally as described above.

In some embodiments, housing 22 and/or lever 28 can each be made ofdifferent materials, e.g., to enhance the grip or “feel” of instrument20. For example, housing 22 and/or lever 28 can be formed of materialswith different hardness, e.g., a core of relatively hard material and anouter layer of relatively soft material. The outer layer can be a foamymaterial, such as a urethane, to enhance the grip and/or to absorbvibrations from the firing of instrument 20. Each of lever 28 and/orhousing 22 can be formed with two or more different materials.

The components of instrument 20 described above can be formed byconventional injection molding techniques, e.g., of polycarbonate and/orABS. Stylet 24, cannula 26, springs 50 and 65, and the torsion springscan be formed of stainless steel.

Terms, such as “left”, “right”, and “rear”, are used to describe theembodiment as shown in the orientation of the figures, and not intendedto be limiting.

Other embodiments are within the claims.

1. A medical instrument, comprising: a housing; a stylet having aportion in the housing, the stylet being movable between an extendedposition and a retracted position; a cannula coaxially receiving thestylet and having a portion in the housing, the cannula being movablebetween an extended position and a retracted position; and a levercoupled to the housing, wherein, by movements of the lever from a firstposition spaced apart from the housing towards a second position closerto the housing, the lever is capable of sequentially moving the styletfrom the extended position to the retracted position, and moving thecannula from the extended position to the retracted position.
 2. Theinstrument of claim 1, wherein the cannula is retracted before thestylet is retracted.
 3. The instrument of claim 1, wherein the lever ispivotally coupled to the housing.
 4. The instrument of claim 1, furthercomprising a cannula block attached to a proximal end of the cannula,the cannula block comprising an engaging element capable of releasablyholding the cannula in the retracted position.
 5. The instrument ofclaim 4, wherein the engaging element engages with the housing when thecannula is in the retracted position.
 6. The instrument of claim 4,further comprising a linkage attached to the lever, the linkage beingengageable with the cannula block to move the cannula to the retractedposition.
 7. The instrument of claim 1, further comprising: a styletblock attached to a proximal end of the stylet; and a latch in thehousing, the latch and the stylet block engaging when the stylet is inthe retracted position.
 8. The instrument of claim 7, further comprisinga linkage attached to the lever, the linkage being engageable with thestylet block to move the stylet to the retracted position.
 9. Theinstrument of claim 7, further comprising a first trigger engageablewith the latch to release the stylet from the retracted position. 10.The instrument of claim 9, wherein the first trigger pivotally moves thelatch to disengage the latch from the stylet block.
 11. The instrumentof claim 9, further comprising a second trigger engageable with thelatch to release the stylet from the retracted position.
 12. Theinstrument of claim 1, further comprising: a stylet block attached to aproximal end of the stylet; a cannula block attached to a proximal endof the cannula; and a linkage attached to the lever, the linkage capableof being in a first position in which the linkage is engageable with thecannula block to move the cannula to the retracted position withoutmoving the stylet block, and in a second position in which the linkageis engageable with the stylet block to move the stylet to the retractedposition.
 13. The instrument of claim 1, further comprising a firsttrigger configured to release the stylet from the retracted position.14. The instrument of claim 13, wherein the first trigger is located ata proximal end of the housing.
 15. The instrument of claim 13, whereinthe first trigger and the lever are located on opposing surfaces of thehousing.
 16. The instrument of claim 13, further comprising a secondtrigger configured to release the stylet from the retracted position.17. The instrument of claim 1, further comprising a lock engageable withthe lever when the stylet block is in the retracted position.
 18. Theinstrument of claim 1, further comprising an indicator capable of beingin a condition representative of when the stylet is in the retractedposition.
 19. The instrument of claim 18, wherein the indicator iscapable of providing a change in color.
 20. The instrument of claim 18,wherein the indicator is capable of providing a change in symbol. 21.The instrument of claim 1, further comprising: a first triggerconfigured to hold the stylet in the retracted position; and a secondtrigger engageable with the first trigger, wherein the first and secondtriggers are configured to release the stylet from the retractedposition.
 22. The instrument of claim 21, wherein the first trigger ispivotally attached to the housing.
 23. The instrument of claim 21,wherein the first trigger has a proximal end, and the second trigger hasa distal end configured to engage with the proximal end of the firsttrigger.
 24. The instrument of claim 21, wherein the proximal and distalends are angled.
 25. A medical instrument, comprising: a housing; astylet having a portion in the housing, the stylet being movable betweenan extended position and a retracted position; a cannula coaxiallyreceiving the stylet and having a portion in the housing, the cannulabeing movable between an extended position and a retracted position; alever coupled to the housing; and a linkage attached to the lever, thelinkage capable of being in a first position in which the linkage iscapable of moving the cannula to the retracted position without movingthe stylet, and in a second position in which the linkage is capable ofmoving the stylet to the retracted position; wherein the first positionis different than the second position.
 26. The instrument of claim 25,wherein the lever is pivotally coupled to the housing.
 27. Theinstrument of claim 25, further comprising two triggers configured torelease the stylet from the retracted position.
 28. The instrument ofclaim 25, further comprising an indicator capable of being in acondition representative of when the stylet is in the retractedposition.
 29. A medical instrument, comprising: a housing; a stylethaving a portion in the housing, the stylet being movable between anextended position and a retracted position; a cannula coaxiallyreceiving the stylet and having a portion in the housing, the cannulabeing movable between an extended position and a retracted position; anda lever coupled to the housing, wherein, by sequential movements of thelever from a first position spaced apart from the housing towards asecond position closer to the housing, the lever is capable of movingthe stylet from the extended position to the retracted position, andmoving the cannula from the extended position to the retracted position.